Cooling system



Aug. 4, 1942. A. scHElBE coOLINGsYsTEM l -Filed March 29, 1940 Jnven'rop: #nf/Mo .sms/55,

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Patented Aug. 4, 1942 UNITED STATES PATENT OFFICE v 'oooruss'rnm Alfred Scheileggssau-Ziebigk, Germany, assignor o Flugzeug-und-Motorenwerke- Aktiengesellschaft, a corporation of Germany Application March 29, 1940, Serial N I e bruary 25, 1

n G many 4 Claims.

This invention is directed to a cooling system for an internal combustion engine. ticularly, the invention is directed to regulating the temperature and pressure in a gas and fluid separating device for the cooling system.

1n cooling systems for internal combustion engines, particularly aircraft engines, it has been known to separate steam before the cooling water is recirculated by a pump back to the engine. The steam and water mixture coming from an engine running at normal speed, enters the separator and creates a pressure slightly greater than the atmospheric pressure within the separator. This increase in pressure raises the boilingv point ofthe water and only the quantity of steam boiled from the water higher temperatures is separated oi. Separated steam 4is then conducted to a condenser, and from the condenser is returned to the circulating system for the engine. Normally the condenser operates under atmosphericpres rise to certain disturbances when the engine operationis varied. For example, if the engine has become heated byv running at a relatively high speed, and then is suddenly slowed, the engine driven cooling pump is slowed and circulates the water through the engine at a less rapid rate. The water, during its engine, absorbs a greater than normal amount of heat as it is cooling the previously heated engine. The pump is also slowed, and the water correspondingly enters the separator at a lessened pressure. Thus the boiling point of the more highly heated water, or the temperature at which the steam separates is lowered. Consequently at this lower boiling point, a greater amount of steam is separated oi than if the pressure were not so lowered. Such an excessof steam may be greater than the capacity of the condenser, and if the condenser is open to the atmosphere, there would be a loss of steam into the atmosphere. This is quite objectionable, inasmuch as the cooling system for the engine is designed for a certain quantity tity of uid will cause serious operating difficulties. Furthermore, an excess of steam in the condenser may mean that steam is passed with back into the cooling system for the engine, and consequently steam pockets will be formed in the system, which produce fluid surges and unequal heating therein. Even the inclusion of so-called equalizing chambers open to the atmosphere in the condenser circuit fail to eliminate these diiiculties.

It is an object of this invention to provide means for preventing a sudden drop in the boiling point of the fluid in the cooling system at a time when an excess oi steam is generated.

Another object oi the invention is to provide More parfrom the cooling waterv (Cl. 12R-174) means for gradually 'reducing the boiling point of the cooling fluid at a rate commensurate with the rate oi engine cooling, so that excess steam will notbe separated from the fluid. I

Another object of the invention is to create a' temporary static excess pressure upon the cooling system of an engine when the dynamic pressure thereof is suddenly lowered, so that the pressure of the system can be gradually dropped at a controlled rate.

A further object of the invention is to provide means for preventng an excess of steam being passed to the condenser of a cooling system for an internal combustion engine when the circulationv rate of the cooling fluid through the engine has been reduced. A -V A` further object of the invention is to create 'a primary cooling system for an engine, in which the pump and separator are combined, and an auxiliarysystem for condensing separated steam and returning the condensate to the pump while preventing the formation of excess steam in t combined pump and separator.

Generally these objects of the invention are obtained by combining the water pump and the steam and water separator into a singl auxiliary circuit attached to this unitv comprises a steam pressure chamber in a condensing system so that the back pressure from this chamber to the steam and water separator will retard the lowering of the boiling point of the cooling iiuid. A pressure release device is joined to the pressure chamber so that the pressure therein is gradually lowered to atmospheric pressure over a length of time commensurate with the cooling of the engine. `This pressure release device canv take the form oi a bafiled passage, a spring loaded valve, or a combination of the two. The condensate in the auxiliary circuit is returned directly to the blades of the pump. I

The means by which the objects of the invention are obtained are more fully understood with reference to the accompanying drawing, in which:

Fig. 1 .is a diagrammatic side elevational view, partly insection, showing the cooling system of an internal combustion engine;

Fig. 2 is a side elevational view, partly in section, showing a modified construction of the steam pressure chamber in the condenser and 3 is an enlarged detail view of a portion of Fig. 1.

In Fig. 1, the cooling system for the internal combustion engine lis composed of a. pump 4 joined to the engine f 8f Pump diS- charge line 6 and a pump feed line 8. Pump l is illustrated as a centrifugal pump driven from the engine through shaft I0.

- In the construction shown, 6 separator is combined with the steam and water the pump I. The

system i pressure equalizing device comprises fluid feed line 8 communicates with a chamber l2 in the pump housing I4. 'Ihe steam and water mixture entering chamber I2 flows through ports I6 into the blades I8 of pump 4. Pump 4 therefore actually comprises a centrifugal pump and a centrifugal steam and water separator. Steam separated from the water collects in chamber 28, from which it is conducted through pipe 22 to condenser 24. 'Ihe condensate is passed from condenser 24 through pipe 26 into a chamber 28 which functions as a steam pressure chamber, as later described.

condensate from chamber 28 is returned to the pump through pipe 30 which, according to the form of pump shown, communicates with a chamber 32 surrounding pump drive shaft I0. Boresf84 in the pump impeller permit the condensate to pass from chamber 32 to the discharge side of the pump.

When the engine is operating at a relatively high speed, a quantity of cooling iiuid is circulated by pump 4 through the engine at a velocity commensurate with the speed at which the pump is being driven by the engine. At normal operating speeds of the engine, the luidenters the separator at a pressure slightly greater than atmospheric pressure, the uid thus having a relatively high boiling point.

If the engine is suddenly slowed, for example, to idling speed, the velocity of the cooling liquid flowing through the engine is reduced, and the cooling iliiid at this reduced velocity absorbs the heat generated in the engine while the engine was operated at the higher speed. If the separator were opened to atmospheric pressure, the reduced velocity of the uid in the separator would mean that the boiling point of the mixture would correspondingly drop, and steam would be released from,the more highly heated fluid at this low'ered boiling point. `Thus a greater quantity of steam would separate from the fluid than if the boiling point of the huid were maintained at a higher value. Such an excess of steam may be beyond the capacity of the condenser.

To prevent suchan excess of.steam from being separated from the fluid in the separator, this invention provides the steam pressure chamber 28. When an excess of steam is generated when the motor is slowed, a rise in pressure is produced inthe chamber 28,

static increase in pressure to prevent the boiling point of the water from being lowered. The pressure in chamber 28 is gradually reduced by means of a pressure equalizing device connected to steam chamber 28. As shown in Figs. lA

a housing 36 having a plurality of baille plates 38 therein, these plates defining a tortuous passage from the interior of chamber 28 to the atmosphere. The rate of pressure equalizing from chamber 28 is made approximately equal to the rate of the cooling of engine 2, so that the pressure and temperature of the water in the separator are gradually lowered without the production of excess steam. In order to obtain a more controlled reduction of the pressure in the steam chamber 28, the ap paratus of Fig. 2 may be used. In thisiigure the pressure chamber 28 is enclosed within a vessel 40, which vessel is provided with a manually adjustable spring valve 42. It is clear that valve 2 can be adjusted to allow the pressure within chamber 28 to be lowered at any rate desired.

Therefore the objects of the invention are sat- A and 3, this cof ised as when the dvnamic pressure of the cooling iiud is lowered by a reduction in pump speed and more heat is absorbed bythe :duid from the engine, the initial release of excess steam caused by the lowering of the boiling point of the fluid, produces a static back pressure upon the fluid so that the uid will not boil at atmospheric pressure. Excess steam is prevented from being circulated through the engine, and from interfering with the delivery eiliciency of the pump. Furthermore, the static pressure is gradually released so that the pressure in the separator is eventually eqlllaglized with the atmosphere as the engine coo Having now described a means by which the objects of this invention may be obtained, what I claim as new and desire to secure by Letters Patent is:

l.' claim:

said tank and the atmosphere for throttling the escape oi steam from said tank and retarding the equalization of pressure between the interior land exterior of said tank.

the centrifugal pump.

3. A coolingsystem for an internal combustion engine comprising an engine-driven combined whereby the equalization of pressure between the interior and exterior of said tank is retarded.

` an internal combusengine-driven com- 

